# Module 'efipath' -- common operations on EFI pathnames
"""Common pathname manipulations, EFI version. 

Instead of importing this module directly, import os and refer to this
module as os.path.
"""

import os
import stat
import string

# strings representing various path-related bits and pieces
curdir = '.'
pardir = '..'
extsep = '.'
sep = '\\'
pathsep = ';'
altsep = '/'
defpath = '.;fs0:\\Python'
devnull = 'nul'

# Normalize the case of a pathname and map slashes to backslashes.
# Other normalizations (such as optimizing '../' away) are not done
# (this is done by normpath).

def normcase(s):
    """Normalize case of pathname.

    Makes all characters lowercase and all slashes into backslashes."""
    return string.lower(string.replace(s, "/", "\\"))


# Return wheter a path is absolute.
# Trivial in Posix, harder on the Mac or MS-DOS.
# For DOS it is absolute if it starts with a slash or backslash (current
# volume), or if a pathname after the volume letter and colon / UNC resource
# starts with a slash or backslash.

def isabs(s):
    """Test whether a path is absolute"""
    s = splitdrive(s)[1]
    return s != '' and s[:1] in '/\\'


# Join two (or more) paths.

def join(a, *p):
    """Join two or more pathname components, inserting "\\" as needed"""
    path = a
    for b in p:
        if isabs(b):
            path = b
        elif path == '' or path[-1:] in '/\\':
            path = path + b
        else:
            path = path + os.sep + b
    return path


# Split a path in a drive specification (a device followed by a
# colon) and the path specification.
# It is always true that drivespec + pathspec == p
def splitdrive(p):
    """Split a pathname into drive and path specifiers. Returns a 2-tuple
"(drive,path)";  either part may be empty"""
    Drive = ''
    Path = ''
    colon = string.find(p, ':')
    if colon != -1:
        # Separate the drive and path
        Tokens = string.splitfields(p, ':')
        Drive = Tokens[0] + ':'
        if len(Tokens) > 1 and len(Tokens[1]) > 0:
            Path = Tokens[1]
        #
    else:
        Path = p
    #
    return Drive, Path


# Split a path in head (everything up to the last '/') and tail (the
# rest).  After the trailing '/' is stripped, the invariant
# join(head, tail) == p holds.
# The resulting head won't end in '/' unless it is the root.

def split(p):
    """Split a pathname.

    Return tuple (head, tail) where tail is everything after the final slash.
    Either part may be empty."""

    d, p = splitdrive(p)
    # set i to index beyond p's last slash
    i = len(p)
    while i and p[i-1] not in '/\\':
        i = i - 1
    head, tail = p[:i], p[i:]  # now tail has no slashes
    # remove trailing slashes from head, unless it's all slashes
    head2 = head
    while head2 and head2[-1] in '/\\':
        head2 = head2[:-1]
    head = head2 or head
    return d + head, tail


# Split a path in root and extension.
# The extension is everything starting at the last dot in the last
# pathname component; the root is everything before that.
# It is always true that root + ext == p.

def splitext(p):
    """Split the extension from a pathname.

    Extension is everything from the last dot to the end.
    Return (root, ext), either part may be empty."""
    root, ext = '', ''
    for c in p:
        if c in ['/','\\']:
            root, ext = root + ext + c, ''
        elif c == '.':
            if ext:
                root, ext = root + ext, c
            else:
                ext = c
        elif ext:
            ext = ext + c
        else:
            root = root + c
    return root, ext


# Return the tail (basename) part of a path.

def basename(p):
    """Returns the final component of a pathname"""
    return split(p)[1]


# Return the head (dirname) part of a path.

def dirname(p):
    """Returns the directory component of a pathname"""
    return split(p)[0]


# Return the longest prefix of all list elements.

def commonprefix(m):
    "Given a list of pathnames, returns the longest common leading component"
    if not m: return ''
    prefix = m[0]
    for item in m:
        for i in range(len(prefix)):
            if prefix[:i+1] <> item[:i+1]:
                prefix = prefix[:i]
                if i == 0: return ''
                break
    return prefix


# Get size, mtime, atime of files.

def getsize(filename):
    """Return the size of a file, reported by os.stat()"""
    st = os.stat(filename)
    return st[stat.ST_SIZE]

def getmtime(filename):
    """Return the last modification time of a file, reported by os.stat()"""
    st = os.stat(filename)
    return st[stat.ST_MTIME]

def getatime(filename):
    """Return the last access time of a file, reported by os.stat()"""
    st = os.stat(filename)
    return st[stat.ST_MTIME]


# Is a path a symbolic link?
# This will always return false on systems where posix.lstat doesn't exist.

def islink(path):
    """Test for symbolic link.  On EFI always returns false"""
    return 0


# Does a path exist?
# This is false for dangling symbolic links.

def exists(path):
    """Test whether a path exists"""
    try:
        st = os.stat(path)
    except os.error:
        return 0
    return 1


# Is a path a dos directory?
# This follows symbolic links, so both islink() and isdir() can be true
# for the same path.

def isdir(path):
    """Test whether a path is a directory"""
    try:
        st = os.stat(path)
    except os.error:
        return 0
    return stat.S_ISDIR(st[stat.ST_MODE])


# Is a path a regular file?
# This follows symbolic links, so both islink() and isdir() can be true
# for the same path.

def isfile(path):
    """Test whether a path is a regular file"""
    try:
        st = os.stat(path)
    except os.error:
        return 0
    return stat.S_ISREG(st[stat.ST_MODE])


# Is a path a mount point?  Either a root (with or without drive letter)
# or an UNC path with at most a / or \ after the mount point.

def ismount(path):
    """Test whether a path is a mount point (defined as root of drive)"""
    unc, rest = splitunc(path)
    if unc:
        return rest in ("", "/", "\\")
    p = splitdrive(path)[1]
    return len(p)==1 and p[0] in '/\\'


# Directory tree walk.
# For each directory under top (including top itself, but excluding
# '.' and '..'), func(arg, dirname, filenames) is called, where
# dirname is the name of the directory and filenames is the list
# files files (and subdirectories etc.) in the directory.
# The func may modify the filenames list, to implement a filter,
# or to impose a different order of visiting.

def walk(top, func, arg):
    """Directory tree walk with callback function.

    walk(top, func, args) calls func(arg, d, files) for each directory d 
    in the tree rooted at top (including top itself); files is a list
    of all the files and subdirs in directory d."""
    try:
        names = os.listdir(top)
    except os.error:
        return
    func(arg, top, names)
    exceptions = ('.', '..')
    for name in names:
        if name not in exceptions:
            name = join(top, name)
            if isdir(name):
                walk(name, func, arg)


# Expand paths beginning with '~' or '~user'.
# '~' means $HOME; '~user' means that user's home directory.
# If the path doesn't begin with '~', or if the user or $HOME is unknown,
# the path is returned unchanged (leaving error reporting to whatever
# function is called with the expanded path as argument).
# See also module 'glob' for expansion of *, ? and [...] in pathnames.
# (A function should also be defined to do full *sh-style environment
# variable expansion.)

def expanduser(path):
    """Expand ~ and ~user constructs.

    If user or $HOME is unknown, do nothing."""
    if path[:1] <> '~':
        return path
    i, n = 1, len(path)
    while i < n and path[i] not in '/\\':
        i = i+1
    if i == 1:
        if os.environ.has_key('HOME'):
            userhome = os.environ['HOME']
        elif not os.environ.has_key('HOMEPATH'):
            return path
        else:
            try:
                drive=os.environ['HOMEDRIVE']
            except KeyError:
                drive = ''
            userhome = join(drive, os.environ['HOMEPATH'])
    else:
        return path
    return userhome + path[i:]


# Expand paths containing shell variable substitutions.
# The following rules apply:
#       - no expansion within single quotes
#       - no escape character, except for '$$' which is translated into '$'
#       - ${varname} is accepted.
#       - varnames can be made out of letters, digits and the character '_'
# XXX With COMMAND.COM you can use any characters in a variable name,
# XXX except '^|<>='.

varchars = string.letters + string.digits + '_-'

def expandvars(path):  
    """Expand shell variables of form $var and ${var}.

    Unknown variables are left unchanged."""
    if '$' not in path:
        return path
    res = ''
    index = 0
    pathlen = len(path)
    while index < pathlen:
        c = path[index]
        if c == '\'':   # no expansion within single quotes
            path = path[index + 1:]
            pathlen = len(path)
            try:
                index = string.index(path, '\'')
                res = res + '\'' + path[:index + 1]
            except string.index_error:
                res = res + path
                index = pathlen -1
        elif c == '$':  # variable or '$$'
            if path[index + 1:index + 2] == '$':
                res = res + c
                index = index + 1
            elif path[index + 1:index + 2] == '{':
                path = path[index+2:]
                pathlen = len(path)
                try:
                    index = string.index(path, '}')
                    var = path[:index]
                    if os.environ.has_key(var):
                        res = res + os.environ[var]
                except string.index_error:
                    res = res + path
                    index = pathlen - 1
            else:
                var = ''
                index = index + 1
                c = path[index:index + 1]
                while c != '' and c in varchars:
                    var = var + c
                    index = index + 1
                    c = path[index:index + 1]
                if os.environ.has_key(var):
                    res = res + os.environ[var]
                if c != '':
                    res = res + c
        else:
            res = res + c
        index = index + 1
    return res


# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.

def normpath(path):
    """Normalize path, eliminating double slashes, etc."""
    path = string.replace(path, "/", os.sep)
    prefix, path = splitdrive(path)
    if path[:1] == os.sep:
        prefix = prefix + os.sep
        path = path[1:]
    comps = string.splitfields(path, os.sep)
    i = 0
    while i < len(comps):
        if comps[i] == '.':
            del comps[i]
        elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):
            del comps[i-1:i+1]
            i = i-1
        elif comps[i] == '':
            del comps[i]
        else:
            i = i+1
    # If the path is now empty, substitute '.'
    if not prefix and not comps:
        comps.append('.')
    return prefix + string.joinfields(comps, os.sep)


# Return an absolute path.
def abspath(path):
    """Return the absolute version of a path"""
    if not isabs(path):
        path = join(os.getcwd(), path)
    return normpath(path)
